... ARGONNE Ill. Nov. 27 /- Going through airport secur...Scientists at the U.S. Department of Energy's Argonne NationalLaborat...While scientists and engineers have produced microwave radiation using... Right around 1 terahertz you have a range of frequencies where there...

ARGONNE, Ill., Nov. 27 /PRNewswire/ -- Going through airport security
can be such a hassle. Shoes, laptops, toothpastes, watches and belts all
get taken off, taken out, scanned, examined, handled and repacked. But
"T-rays", a completely safe form of electromagnetic radiation, may reshape
not only airport screening procedures but also medical imaging practices.

Scientists at the U.S. Department of Energy's Argonne National
Laboratory, along with collaborators in Turkey and Japan, have created a
compact device that could lead to portable, battery-operated sources of
T-rays, or terahertz radiation. By doing so, the researchers, led by Ulrich
Welp of Argonne's Materials Science Division, have successfully bridged the
"terahertz gap" -- scientists' name for the range of frequencies between
microwaves (on the lower side) and infrared (on the higher side) of the
electromagnetic spectrum.

While scientists and engineers have produced microwave radiation using
conventional electric circuits for more than 50 years, Welp said, terahertz
radiation could not be generated that way because of the physical
limitations of the semiconducting circuit components.

"Right around 1 terahertz, you have a range of frequencies where there
have never been any good solid-state sources," he added. "You can make
those frequencies if you are willing to put together a whole table full of
expensive equipment, but now we've been able to make a simple, compact
solid-state source."

Unlike far more energetic X-rays, T-rays do not have sufficient energy
to "ionize" an atom by knocking loose one of its electrons. This ionization
causes the cellular damage that can lead to radiation sickness or cancer.
Since T-rays are non-ionizing radiation, like radio waves or visible light,
people exposed to terahertz radiation will suffer no ill effects.
Furthermore, although terahertz radiation does not penetrate through metals
and water, it does penetrate through many common materials, such as
leather, fabric, cardboard and paper.

These qualities make terahertz devices one of the most promising new
technologies for airport and national security. Unlike today's metal or
X-ray detectors, which can identify only a few obviously dangerous
materials, checkpoints that look instead at T-ray absorption patterns could
not only detect but also identify a much wider variety of hazardous or
illegal substances. T-rays can also penetrate the human body by almost half
a centimeter, and they have already begun to enable doctors to better
detect and treat certain types of cancers, especially those of the skin and
breast, Welp said. Dentists could also use T-rays to image their patients'
teeth. The new T-ray sources created at Argonne use high-temperature
superconducting crystals grown at the University of Tsukuba in Japan. These
crystals comprise stacks of so-called Josephson junctions that exhibit a
unique electrical property: when an external voltage is applied, an
alternating current will flow back and forth across the junctions at a
frequency proportional to the strength of the voltage; this phenomenon is
known as the Josephson effect.

These alternating currents then produce electromagnetic fields whose
frequency is tuned by the applied voltage. Even a small voltage -- around
two millivolts per junction -- can induce frequencies in the terahertz
range, according to Welp.

Since each of these junctions is tiny -- a human hair is roughly 10,000
times as thick -- the researchers were able to stack approximately 1,000 of
them on top of each other in order to generate a more powerful signal.
However, even though each junction would oscillate with the same frequency,
the researchers needed to find a way to make them all radiate in phase.
"That's been the challenge all along," Welp said. "If one junction
oscillates up while another junction oscillates down, they'll cancel each
other out and you won't get anything." In order to synchronize the signal,
Argonne physicist Alexei Koshelev suggested that the stacks of Josephson
junctions should be shaped into resonant cavities, which visiting scientist
Lufti Ozyuzer of the Izmir Institute of Technology, Turkey, and graduate
student Cihan Kurter then fashioned. When the width of the cavities was
precisely tuned to the frequencies set by the voltage, the natural
resonances of the structure synchronized the oscillations and thus
amplified the T-ray output, in a method similar to the production of light
in a laser.

"Once you apply the voltage," Welp said, "some junctions will start to
oscillate. If those have the proper frequency, an oscillating electric
field will grow in the cavity, which will pull in more and more and more of
the other junctions, until in the end we have the entire stack
synchronized." By keeping the length and thickness of the cavities constant
while varying their width between 40 and 100 micrometers, the researchers
were able to generate frequencies from 0.4 to 0.85 terahertz at a signal
power of up to 0.5 microwatts. Welp hopes to expand the range of available
frequencies and to increase the strength of the signal by making the
Josephson cavities longer or by linking them in arrays.

"The more power you have, the easier it is to adopt this technology for
all sorts of applications," he said. "Our data indicate that the power
stored in the resonant cavities is significantly larger than the detected
values, though we need to improve the extraction efficiency. If we can get
the signal strength up to 1 milliwatt, it will be a great success."

Collaborators on this research were Lutfi Ozyuzer, Alexei Koshelev,
Cihan Kurter, Nachappa(sami) Gopalsami, Qing'An Li, Ken Gray, Wai-Kwong
Kwok and Ulrich Welp of Argonne; Masashi Tachiki from the University of
Tokyo; Kazuo Kadowaki, Takashi Yamamoto, Hidetoshi Minami and Hayato
Yamaguchi from the University of Tsukuba; and Takashi Tachiki from the
National Defense Academy of Japan.

The research was supported by DOE's Office of Basic Energy Sciences and
by Argonne's Laboratory Directed Research and Development funds.

A scientific paper based on their research, "Emission of Coherent THz
Radiation from Superconductors," appears in the November 23 issue of
Science.

Argonne National Laboratory, a renowned R&D center, brings the world's
brightest scientists and engineers together to find exciting and creative
new solutions to pressing national problems in science and technology. The
nation's first national laboratory, Argonne conducts leading-edge basic and
applied scientific research in virtually every scientific discipline.
Argonne researchers work closely with researchers from hundreds of
companies, universities, and federal, state and municipal agencies to help
them solve their specific problems, advance America's scientific leadership
and prepare the nation for a better future. With employees from more than
60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S.
Department of Energy's Office of Science

(Date:12/9/2016)... LLC announced today that Steven E. Dawson has been appointed as chief ... Photo - http://photos.prnewswire.com/prnh/20161209/447552 ... Harmar ... Mr. Dawson,s executive career includes leadership roles managing and executing transformation, ... brings to the company deep operational and leadership expertise, a strong financial ...

(Date:12/9/2016)... Research and Markets has announced the addition of the ... ... travel vaccines market to grow at a CAGR of 6.83% during ... and the growth prospects of the global travel vaccines market for ... generated from the sales of various vaccines administered to actively immunize ...

(Date:12/8/2016)... 8, 2016 IRIDEX Corporation (NASDAQ: IRIX ... shares of common stock, $0.01 par value (the "Offering" with ... offering. The final terms of the Offering will depend on ... there can be no assurance as to whether or when ... use the net proceeds it will receive from this offering ...